Ocular comfort requires the maintenance of a continuous film known as preocular tear film or lachrymal film on the ocular surface, and proper function of the lids to regularly re-spread the tear film before it breaks down.
Dry eye, also known as dysfunctional tear syndrome, is one of the most frequently encountered ocular morbidities and one of the most common disease conditions diagnosed by eye care practitioners. Dry eye has a wide range of signs, symptoms and underlying etiologies. Dry eye is a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. It is accompanied by increased osmolarity of the tear film and inflammation of the ocular surface. Dry eye can be caused by a multitude of causes, such as neural loop dysfunction, mucin deficiency (e.g. goblet cell deficiency or goblet cell dysfunction), primary or secondary inflammation, meibomitis, and lachrymal gland dysfunction as a result of, for example, autoimmune disease (e.g. Sjogren's disease), dysfunctional innervation and damage to the ocular glands.
Excess evaporation of the tear film, usually caused by meibomian gland dysfunction or related lid disorder, is a major underlying feature of dry eye. As a result, symptoms include unpleasantness in the eyes, itchiness, redness, excessive tearing, discomfort after periods of eye strain, inflammation, and damage to the ocular surface.
Management of dry eye has conventionally been achieved by use of lubricant eye drops to provide temporary symptomatic relief, surgical procedures such as punctal plugs, or, more recently, pharmacological therapy for underlying inflammation with cyclosporine A. Other pharmacological agents are currently in development, but initial therapy for most new patients with dry eye consists of artificial tear formulations. There are a number of different artificial tear formulations for medicinal purposes currently on the market. None of these formulations has the physico-chemical properties of real tears.
It would be advantageous to provide an ophthalmic formulation which more closely mimics the physico-chemical properties of tear lipids.